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Gravitational Wave Detection with Optical Lattice Atomic Clocks

June 14, 2016

Fig. S1. Proposed gravitational wave detector (not to scale)

In a new article posted to the arXiv, Harvard Physics graduate Shimon Kolkowitz, postdoc Igor Pikovski, grad student Nick Langellier, and Professors Ronald Walsworth, Mikhail Lukin, and Jun Ye (JILA) propose a space-based gravitational wave detector. This detector will consist of two spatially separated, drag-free satellites sharing ultra-stable optical laser light over a single baseline. Each satellite will contain an optical lattice atomic clock, which serves as a sensitive, narrowband detector of the local frequency of the shared laser light. A synchronized two-clock comparison between the satellites will be sensitive to the effective Doppler shifts induced by incident gravitational waves (GWs) at a level competitive with other proposed space-based GW detectors, while providing complementary features.

The detected signal is a differential frequency shift of the shared laser light due to the relative velocity of the satellites, rather than a phase shift arising from the relative satellite positions, and the detection window can be tuned through the control sequence applied to the atoms’ internal states. This scheme enables the detection of GWs from continuous, spectrally narrow sources, such as compact binary inspirals, with frequencies ranging from ∼3 mHz - 10 Hz without loss of sensitivity, thereby bridging the detection gap between space-based and terrestrial GW detectors. The proposed GW detector employs just two satellites, is compatible with integration with an optical interferometric detector, and requires only realistic improvements to existing ground-based clock and laser technologies.